1. Field of the Invention
This invention relates to a vortex blower of an improved construction formed with at least one projecting wall extending into the suction port or discharge port for reducing noise.
2. Description of the Prior Art
In one type of vortex blower of the prior art, the suction port and the discharge port are arranged on both sides of a partition wall and are communicated with each other by an annular air passageway in a casing in which the impeller is located. This type of vortex blower has had the problem that noise is produced in the vicinity of the partition wall. This problem has been believed to stem from the fact that a sudden change in pressure occurs in the vicinity of the partition wall each time a blade of the impeller passes by the partition wall and that the drawn air vigorously impinges on the impeller on the suction side while the air of increased pressure that has flowed through the air passageway vigorously impinges on the partition wall on the discharge side.
To obviate this problem, Japanese Utility Model Registration No. 967175 (Utility Model Publication No. 31322/71) has been proposed. In this proposal, the a portion of the partition wall, particularly the forward end of its central portion, projects greatly in such a manner that its thickness gradually becomes smaller in a direction extending away from the partition wall and the surface thereof facing the impeller gradually becomes smaller in size, so that the partition wall has extension walls in the form of a triangular vane. The provision of extension walls of this shape enables the noise produced to be reduced to a certain extent because the direction in which the air current flows can be gradually varied in the vicinity of the partition wall and the change in pressure in this zone can be reduced. However, this construction has been unable to achieve the desired results and improvements have been pined sought after.